WASHINGTON — For the first time, scientists have observed an asteroid breaking apart, crumbling
into at least 10 pieces in sort of a celestial, slow-motion train wreck.

The rocky asteroid, named P/2013 R3, was one of the innumerable objects populating the crowded
asteroid belt between the orbits of Mars and Jupiter, roughly three times farther away from the sun
than Earth is.

Asteroids have broken apart many times over the eons, but never before have scientists been able
to witness it.

This time, however, scientists first noticed the dramatic events using ground-based telescopes
in Arizona and Hawaii, and then they got a better look using the Hubble Space Telescope.

“After looking at the asteroid belt for a couple of hundred years — the first one was discovered
in 1801 — to find a new thing like this is really exciting,” said David Jewitt, a University of
California-Los Angeles astronomer who led the research.

The findings were published in the scientific publication
Astrophysical Journal Letters.

The asteroid was probably about 2,000 feet in diameter, and no more than about 3,280 feet in
diameter, before it began to disintegrate, Jewitt said. The breakup unfolded over several months
last year.

The Hubble telescope detected at least 10 fragments, each with a cometlike dust tail. The four
largest pieces had a diameter of up to about 1,300 feet.

The scientists do not think the asteroid was destroyed in a collision with another object. That’s
in part because of how it broke apart — fragments drifted slowly at around 1 mph, which does not
suggest a violent impact.

Instead, the scientists said the breakup was probably the result of sunlight over many, many
years. That likely caused the asteroid to spin at a slowly increasing rate until it became unstable
and ruptured.